This invention relates to roofing shingles, and more specifically to laminated roofing shingles and a method for producing such shingles.
Laminated roofing shingles, which are also sometimes called architectural shingles, have become widely used in the roofing industry. These shingles provide many advantages over other types of roofing materials, but the primary advantage and attraction with these products is the attractive appearance they provide when applied to a structure.
There are many styles, types and manufacturers of laminated shingles. Like most all shingles, laminated shingles have a length dimension and a width dimension, and these dimensions are somewhat standard in the industry. In general, laminated shingles are characterized in their having two or more layers of asphaltic roofing material overlaid upon one another and bonded together to provide a shingle having thicker sections. The upper layer of the shingle has alternating xe2x80x9ctabsxe2x80x9d and cutout portions in the lowermost edge of the shinglexe2x80x94that is, the edge of the shingle that is found on the downhill side of the shingle when the shingle is applied to a sloped roof. The lower layer underlies at least the tabbed portion of the upper layer.
The length dimension of the two sheets of a laminated shingle is typically the same. However, the width dimension generally is not. Nonetheless, it is possible to manufacture a laminated shingle having a lower layer and an upper layer having the same peripheral dimensions, and some manufacturers do make such shingles.
The most common kind of laminated shingle has a lower layer called a backing sheet and an upper layer laminated to the backing sheet. As noted, the upper layer has tabs cut into the lower edge. The two sheets are not coextensive in the width dimension; the backing sheet is not as wide as the upper layer. Instead, the backing sheet extends only partially up the width of the upper layer, and generally extends only a short distance past the extent of the tabs that are cut into the upper layer.
When laminated shingles are applied to a roof, nails or other fasteners must be applied to through two layers of shingle material. The nails must be applied above the headlap marginxe2x80x94that area above the upper margin of the cutout portions of the top sheetxe2x80x94and below the upper margin of the backing sheet. Nails thus may be placed in a zone that extends along the length of the shingle, the so-called xe2x80x9cnail zone.xe2x80x9d
Nail application through a double layer of asphaltic material (i.e., in the nail zone) is essential to proper installation of laminated shingles, and is required by most shingle manufacturers. In addition, many local building codes refer to manufacturers recommended installation instructions for guidance on proper roof installation. There are good reasons for this requirement. First, nailing through a double layer of material provides strength, which is essential for roofing integrity in windy conditions. Second, if a laminated shingle is applied with nails placed through just the upper layer of the shingle, above the nail zone, it is possible for the backing sheet to slip out from under the upper layer. This may happen, for instance, on a roof having a steep slope during hot weather when the compounds used to bond the layers of the laminates togetherxe2x80x94typically an asphaltic compoundxe2x80x94become flowable. This obviously causes severe damage to a roof.
One of the critical issues, therefore, in designing a laminated shingle is to provide a nail zone that facilitates consistent nail application in the proper location. Another somewhat diametrical consideration taken into account when designing laminated shingles is packaging the shingles for shipping and storage. Shingles are typically bundled in stacks with an overwrapping material. Since the two sheets in most laminated shingles are not coextensive in the width dimension, stacking the shingles in the same orientation above one another would result in a stack and bundle that is not flat. That is, some portions of the stack would have more layers of sheet material than others, so the entire stack would not be flat and instead would have a bow in it. This is unacceptable, since many bundles of shingles must be loaded onto, for instance, pallets for shipping. If the bundles are not flat, they cannot be stacked on a pallet with good stacking integrity.
A standard solution to this problem is to first build the laminated shingle such that the backing sheet extends no more than xc2xd of the distance of the top sheet in the width dimension. Then, two of this kind of shingle may be paired with one another such that they are oriented in opposite directions. This results in a pair of laminated shingles oriented in opposite directions with respect to one another, and which will lie flat when stacked since each pair of shingles will have three layers of shingle at all points in the stack. Multiple pairs of shingles oriented in this fashion may then be bundled into flat bundles, which are well suited for shipping and storage.
There are several variations on this basic stacking theme with laminated shingles that have a backing sheet that is no more than xc2xd the width of the top sheet. However, this solution leads to several problems. Most notably, such shingles have a nail zone that is relatively narrow. Thus, the width of the nail zone is constrained by two factors. First, the nail zone must be far enough beyond the limits of the tabs on the upper layer to insure that the nails are well-removed from exposure to the weather and are covered by the next overlying course of shingles. Second, the nails must be applied through a double layer of materialxe2x80x94thus, through the nail zone.
The problems with laminated shingles having narrow nail zones are notorious in the industry. Most laminated shingles are applied by roofers who use automatic nailing or stapling guns such as pneumatic guns. These workers typically want to apply the roofing as quickly as possiblexe2x80x94there are obvious economic advantages in doing so since the roofer may be paid by how much roofing is applied. However, a narrow nail zone combined with high speed pneumatic nailing guns and a desire to apply shingles rapidly makes a recipe for trouble, and improper nail application has often been the result. In fact, it has been observed that the vast majority of roofs with laminated shingles have many, many improperly applied shingles, and perhaps over 50% of all laminated shingles include at least some nails driven through only one sheet. Most importantly, this compromises the integrity of the roofing. It also may violate code restrictions for proper application of the roofing materials. With a typical roof containing somewhere between 5,500 and 7,500 nails, there are many opportunities for misplaced nails when they are not carefully applied.
Despite these limitations with laminated shingles, the vast majority of these products are manufactured as noted above with a relatively narrow nail zone. There is a need therefore for a laminated shingle product that is aesthetically pleasing yet makes proper installation easier, that is, installation with the fasteners applied through two sheets, and which is readily stacked, bundled and shipped.
The laminated shingle of the present invention addresses these concerns in a different manner. The shingles start with asphaltic roll stock that is wider than traditional roll stock. The roll stock is then manufactured such that the outer marginal edges have a relatively thinner zone than the remainder of the material. This roll stock is then cut and formed into a laminated shingle in a standard manner. However, the nail zone is substantially wider than traditional laminated shingles because the wider roll stock allows for a wider backing sheet. This wider nail zone has two layers of asphaltic material through which the nails may be rapidly driven. Given the substantially increased width of the nail zone, the nails seldom miss their intended mark.
Stacking, bundling and shipping the laminated shingle of the present invention also is not a problem. While the backing sheet of the present laminated shingle is substantially greater than xc2xd of the width of the top sheet, which thus results in the wider nail zone, the wider portion of the backing sheet is relatively thinner than the remainder of the sheet. This therefore allows shingles to be paired with one another in a traditional manner, as described above, and stacked with multiple additional pairs of shingles, but produces a flat stack for bundling and shipping.